Mo. Rev. Stat. § 67.5010: Majority vote required.

If a majority of the votes cast by the qualified voters voting on the question submitted pursuant to section 67.5008 voted YES, then that district shall be deemed created. However, if a majority of the qualified voters cast NO votes, that district shall not be deemed created unless and until another question of whether to authorize the creation of a district and impose the one-tenth of one cent local sales tax is submitted to the qualified voters of that county and that question is approved by a majority of the qualified voters voting thereon.